Breast biopsy system and methods

ABSTRACT

An apparatus and method are provided for precisely isolating a target lesion in a patient&#39;s body tissue, resulting in a high likelihood of “clean” margins about the lesion when it is removed for diagnosis and/or therapy. This approach advantageously will often result in the ability to both diagnose and treat a malignant lesion with only a single percutaneous procedure, with no follow-up percutaneous or surgical procedure required, while minimizing the risk of migration of possibly cancerous cells from the lesion to surrounding tissue or the bloodstream. In particular, the apparatus comprises a biopsy instrument having a distal end adapted for entry into the patient&#39;s body, a longitudinal shaft, and a cutting element disposed along the shaft. The cutting element is actuatable between a radially retracted position and a radially extended position. Advantageously, the instrument is rotatable about its axis in the radially extended position to isolate a desired tissue specimen from surrounding tissue by defining a peripheral margin about the tissue specimen. The specimen may be encapsulated and removed as an intact piece.

This application is a divisional of application Ser. No. 09/057,303,filed Apr. 8, 1998, now U.S. Pat. No. 6,331,166 which is herebyincorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to methods and devices for removing tissuesamples, and more specifically to improved instruments and methods foracquiring soft body tissue.

BACKGROUND OF THE INVENTION

It is often desirable and frequently necessary to sample or remove aportion of tissue from humans and other animals, particularly in thediagnosis and treatment of patients with cancerous tumors, pre-malignantconditions, and other diseases or disorders.

Typically, in the case of cancer, particularly cancer of the breast,there is a great emphasis on early detection and diagnosis through theuse of screening modalities, such as physical examination, andparticularly mammography, which is capable of detecting very smallabnormalities, often nonpalpable. When the physician establishes bymeans of a mammogram or other screening modality, such as ultrasound,that suspicious circumstances exist, a biopsy must be performed tocapture tissue for a definitive diagnosis as to whether the suspiciouslesion is cancerous. Biopsy may be done by an open or percutaneoustechnique. Open biopsy, which is an invasive surgical procedure using ascalpel and involving direct vision of the target area, removes theentire mass (excisional biopsy) or a part of the mass (incisionalbiopsy). Percutaneous biopsy, on the other hand, is usually done with aneedle-like instrument through a relatively small incision, blindly orwith the aid of an artificial imaging device, and may be either a fineneedle aspiration (FNA) or a core biopsy. In FNA biopsy, individualcells or clusters of cells are obtained for cytologic examination andmay be prepared such as in a Papanicolaou smear. In core biopsy, as theterm suggests, a core or fragment of tissue is obtained for histologicexamination which may be done via a frozen section or paraffin section.

The type of biopsy utilized depends in large part on circumstancespresent with respect to the patient, including the location of thelesion(s) within the body, and no single procedure is ideal for allcases. However, core biopsy is extremely useful in a number ofconditions and is being used more frequently by the medical profession.

A very successful type of image guided percutaneous core breast biopsyinstrument currently available is a vacuum-assisted automatic corebiopsy device. One such successful biopsy device is shown and disclosedin U.S. Pat. No. 5,526,822 to Burbank et al, expressly incorporated byreference herein. This device, known commercially as the MAMMOTOME®Biopsy System, which is available from Ethicon Endo-Surgery, Inc., adivision of Johnson & Johnson, has the capability to actively capturetissue prior to cutting the tissue. Active capture allows for samplingthrough non-homogeneous tissues. The device is comprised of a disposableprobe, a motorized drive unit, and an integrated vacuum source. Theprobe is made of stainless steel and molded plastic and is designed forcollection of multiple tissue samples with a single insertion of theprobe into the breast. The tip of the probe is configured with alaterally disposed sampling notch for capturing tissue samples.Orientation of the sample notch is directed by the physician, who uses athumbwheel to direct tissue sampling in any direction about thecircumference of the probe. A hollow cylindrical cutter severs andtransports tissue samples to a tissue collection chamber for latertesting.

While this type of system functions very well as a core biopsy device,there are occasions when it may be useful to have the capability ofacquiring a relatively large intact tissue sample. One such core biopsydevice is disclosed in U.S. Pat. No. 5,111,828, to Kornberg et al., alsoexpressly incorporated by reference herein. In the device disclosed byKornberg et al., the tissue receiving port is disposed at the distal endof the device and is oriented axially rather than laterally. Adisadvantage of this type of device, however, is the inability toacquire a tissue sample having a cross-section larger than that of thecannula through which the sample will be removed. Additionally, it isdifficult, using such a device, which obtains cylindrical shapedspecimens, to determine whether an entire lesion of interest is beingremoved or whether a further procedure will be necessary. This isparticularly true because most lesions of interest are typicallyspherical in shape, having a diameter of approximately 1 cm. The onlyway one can tell whether the entire lesion has been removed using theKornberg technique is to remove and examine the specimen, determiningwhether each of the margins of the specimen is “clean”, meaning thatthere is no evidence of lesion, or “dirty”, meaning that lesion isevident right to the edge of the specimen. Of course, if one or morespecimen margins is “dirty”, it is almost a certainty that a portion ofthe lesion remains in the patient, and if the biopsy test results on thelesion are positive, a further surgical procedure will be indicated.

It would be desirable, therefore, to have an apparatus and method forisolating a target lesion, with a sufficient border around and beyondthe lesion that the likelihood of “clean” margins is relatively high. Itwould further be advantageous to have an apparatus and method availablefor initially isolating the entire target lesion, by cutting a swathcompletely about the lesion to cut off its blood supply, after which afurther procedure is undertaken to remove it from the patient's body.This approach would help to minimize the migration of possibly cancerouscells from the lesion to surrounding tissue or bloodstream during theremoval procedure.

SUMMARY OF THE INVENTION

The present invention addresses the foregoing problems by providing suchan apparatus and method for precisely isolating a target lesion,resulting in a high likelihood of “clean” margins. This advantageouslywill often result in the ability to both diagnose and treat a malignantlesion with only a single percutaneous procedure, with no follow-uppercutaneous or surgical procedure required, while minimizing the riskof migration of possibly cancerous cells from the lesion to surroundingtissue or the bloodstream.

More particularly, in one aspect of the invention, a biopsy instrumentis provided for retrieving body tissue, which instrument has alongitudinal axis. The instrument comprises a distal end adapted forentry into a patient's body, a shaft disposed along the axis, and acutting element disposed along the shaft. The cutting element isactuatable between a radially retracted position and a radially extendedposition. Advantageously, the instrument is rotatable about its axis inthe radially extended position to isolate a desired tissue specimen fromsurrounding tissue by defining a peripheral margin about the tissuespecimen. Once the tissue specimen is isolated, it may be segmented byfurther manipulation of the cutting element, after which the tissuesegments are preferably individually removed from the patient's bodythrough a cannula or the like. Alternatively, the specimen may beencapsulated and removed as an intact piece.

In another aspect of the invention, an instrument is provided forretrieving body tissue, having a longitudinal axis and comprising adistal end adapted for entry into a patient's body. The instrumentfurther comprises an element for encapsulating a tissue specimen so thatit may be withdrawn as a single unit from the patient's body. Theencapsulating element preferably comprises a plurality of bands disposedalong the instrument axis, each of which are actuatable between aradially retracted position and a radially extended position.

In yet another aspect of the invention, a method is disclosed forretrieving a tissue specimen from a patient's body, comprising the stepsof inserting an instrument having a distal end, a longitudinal axis, andan axially disposed cutting element, into the patient's body, so that adistal end is disposed in a tissue region from which the tissue specimenis to be taken. The cutting element is radially expanded so that aportion thereof is radially outwardly spaced from the axis of theinstrument. Once the cutting element is radially expanded, it is rotatedabout the axis to cut the tissue and create a peripheral boundary aboutthe tissue specimen, to isolate the tissue specimen from surroundingtissue in the tissue region.

The invention, together with additional features and advantages thereof,may best be understood by reference to the following description takenin conjunction with the accompanying illustrative drawing.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a perspective view of the distal end of one preferredembodiment of the inventive tissue retrieval instrument;

FIG. 2 is a perspective view illustrating the distal end of a monopolarembodiment of the inventive tissue retrieval instrument shown in FIG. 1;

FIG. 3 is a perspective view similar to that of FIG. 2, illustrating thedistal end of a bipolar embodiment of the inventive tissue retrievalinstrument shown in FIG. 1;

FIG. 4 is a cutaway view from the side illustrating the internalconstruction of a presently preferred proximal drive unit for operatingthe inventive tissue retrieval instrument;

FIG. 5 is a perspective view from the top illustrating the proximaldrive unit of FIG. 4, with the top portion of the housing removed inorder to show portions of its internal construction;

FIG. 6 is a perspective view from the proximal end illustrating theproximal drive unit of FIGS. 4 and 5, with the top portion of thehousing removed in order to show portions of its internal construction;

FIG. 7 is a perspective view from the distal end illustrating theproximal drive unit of FIGS. 4-6, with the top portion of the housingremoved in order to show portions of its internal construction;

FIG. 8 is a schematic view illustrating the distal end of the instrumentof FIG. 1 disposed in a tissue region from which target tissue is to beretrieved, wherein the distal cutting element is deployed in a firstposition for isolating a first segment of a target tissue specimen fromsurrounding tissue;

FIG. 9 is a schematic view similar to FIG. 8, wherein the distal cuttingelement is deployed in a second position for isolating a second segmentof the target tissue specimen from surrounding tissue;

FIG. 10 is a schematic view similar to FIGS. 8 and 9, wherein the distalcutting element is deployed in a third position for isolating a thirdsegment of the target tissue specimen from surrounding tissue;

FIG. 11 is a perspective view illustrating the distal end of a secondpreferred embodiment of the inventive tissue retrieval instrument;

FIG. 12 is a perspective cutaway view of the distal end of theembodiment of FIG. 11, illustrating the internal construction thereof,including tissue wrapping and cutting elements in their stored position;

FIG. 13 is a perspective cutaway view similar to that of FIG. 12,wherein the sheath has been retracted in order to deploy the tissuewrapping and cutting elements shown in FIG. 12;

FIG. 14 is a side schematic view of the distal end of the embodiment ofFIGS. 11-13, illustrating the deployment of the tissue wrapping andcutting elements shown in FIG. 12;

FIG. 15 is a perspective view illustrating the tissue wrapping andcutting elements of FIGS. 12 and 14 in their fully deployed position;

FIG. 16 is a side view showing the deployed tissue wrapping and cuttingelements after the distal end of the instrument has been rotated totwist the wrapping and cutting elements in order to wrap a target tissuesample;

FIG. 17 is a perspective, schematic view of an alternative embodiment ofthe distal end of the inventive tissue retrieval instrument, wherein thecutting element of the instrument is in a retracted position;

FIG. 18 is a perspective, schematic view similar to FIG. 17,illustrating the cutting element in a deployed position for creatingcylindrical tissue segments; and

FIG. 19 is a perspective, schematic view similar to FIGS. 17 and 18,illustrating the cutting element in a deployed position for creatingtissue segments of varying heights.

DESCRIPTION OF THE INVENTION

Referring now more particularly to FIG. 1, there is shown the distal end12 of a first preferred embodiment of an inventive tissue retrieval orbiopsy instrument 10. The distal end 12 preferably comprises adisposable wand portion, including a distal tip 14. The tip 14 maycomprise a conventional trocar tip, or, preferably, may include anelectrosurgical (RF) element or wire 16 which may be energized by aconventional electrosurgical generator (not shown) in order tofacilitate tissue cutting and consequent advancement of the instrument10 to a predetermined tissue site in the patient's body.

Proximally of the tip 14 is a shaft 18, preferably lying along an axis19 (FIG. 1) of the instrument, on which is disposed a cutting element orwire 20. This wire 20 is disposed axially along the length of the shaft18 in its retracted position (not shown), but may be deployed radiallyoutwardly, as shown in FIG. 1. The element 20 is preferably comprised ofa wire or rectangular band fabricated of memory metal such as Nitinol,though stainless steel, tungsten, or other biocompatible materials couldalso be employed, if desired. The cutting element 20 acts as anelectrosurgical cutter, energizable by means of RF energy provided bythe electrosurgical generator discussed supra. The instrument 10 may bemonopolar, as illustrated in FIG. 2, with the cutting element 20comprising the active electrode and a return electrode spaced from theinstrument 10 and most typically being disposed on the patient's skin inthe form of a patch electrode on the thigh or back. Alternatively, theinstrument 10 may preferably be bipolar, as illustrated in FIG. 3, withthe cutting element comprising the active electrode and a returnelectrode 22 being disposed on the instrument in close proximity to theactive electrode, such as along the shaft 18. With such an arrangement,a layer of insulation 23 is disposed between the return electrode(comprising a major portion of the surface area of the shaft 18) and theportion of the shaft adjacent to the active electrode, which receivesthe cutting element 20 in its retracted position. The bipolar embodimentis generally preferred because of a greater safety factor and lowerpower requirements.

A plurality of cutting wires 20 may be employed if desired, preferablyspaced circumferentially about the shaft 18. In some embodiments, it maybe preferably to have webs between the cutting elements, to create a“sail” rather than entire distinct separate cutting elements.

Referring now more particularly to FIGS. 4-7, a proximal reusable driverportion 24 for the distal end or disposable wand portion 12 is shown.The driver portion 24 is preferably disposed on a stereotactic rail 26,in known fashion, for guidance of the instrument 10 to a predeterminedtissue site using known imaging techniques. Such stereotactic imagingsystems are available, for example, from Fischer, Inc. or Lorad, Inc.Alternative imaging systems, such as mammographic, ultrasonic, CT, MRIguidance systems may be used in place of a stereotactic system, ifdesired. Additionally, the instrument may be guided to the lesion siteusing an articulating arm system or manually, rather than on astereotactic rail.

The reusable driver portion 24 comprises a housing 28 within which isdisposed a coaxial arrangement comprising an outer sheath 30, the shaft18, and a rod 32 which is attached at its distal end to the cutterelement 20. A knob 34 is rotatably attached to the shaft 18 through agearing system 35 to rotate the shaft 18 as desired, for the purpose ofcircumferentially orienting and rotating the cutting element 20. Threelevers 36, 38, and 40 extend outwardly through slots 42, 44, and 46,respectively, in the side of the housing 28. The first lever 36 isactuatable to slide the sheath 30 axially both proximally and distally,for a purpose to be described hereinbelow. The second lever 38 isactuatable to move the shaft 18 axially in distal and proximaldirections, as desired. The third lever 40 is actuatable to move the rod32 axially in distal and proximal directions, as desired. Since the rod32 is attached at its distal end to the proximal end of the wire cutter20, movement of the rod 32 in an axial direction also causes theproximal end of the wire cutter 20 to move in an axial direction. Sincethe distal end of the cutter 20 is anchored to the shaft 18, movement ofthe proximal end of the cutter element 20 in a distal direction causesthe midportion of the cutting element 20 to bow radially outwardly to aradially expanded position, as shown in any of FIGS. 1-3, while movementof the proximal end of the cutter element 20 in a proximal directioncauses the midportion of the cutter element 20 to retract radially toits stowed position, disposed linearly along the axial length of theshaft 18, preferably within a recess 48 (FIG. 1).

An advantageous feature of the invention is the employment of a seriesof stops 50 in the second slot 44, and a series of stops 52 in the thirdslot 46, as illustrated in FIGS. 5-7. The stops 50 enable the secondlever 38 to be actuated to a plurality of discrete axial positions,which in turn permits the shaft 18 to be actuated to a correspondingplurality of discrete axial positions for fine tuning the axial positionof the electrosurgical cutting element 20. Similarly, the stops 52enable the third lever 40 to be actuated to a plurality of discreteaxial positions, which in turn permits the electrosurgical cuttingelement 20 to be radially extended to a corresponding plurality ofradially extended positions, for a purpose to be described more fullyhereinbelow.

With reference now more particularly to FIGS. 8-10, the operation of thefirst preferred embodiment of the inventive device will be explained.Initially, when it is determined that either a diagnostic or therapeuticbiopsy procedure is indicated, the distal disposable wand portion 12 ofthe instrument 10 will be moved axially to a position wherein the distaltip is adjacent to and preferably within a target lesion 54, using thestereotactic rail 26 and associated imaging system. During this processstep, wherein gross linear movement of the wand 12 is controlled by therail system 26, the electrosurgical cutting element 16 on the distal tip14 is energized to pierce and cut through the patient's body tissue 56to permit distal advancement of the wand 12 to the region surroundingthe lesion 54.

Once the distal tip 14 is generally in the desired position adjacent toor within the target lesion 54, using the stereotactic rail 26, thesecond lever 38 is actuated to provide fine tuning of the axial positionof the distal tip 14 relative to the lesion 54, by moving the shaft 18axially to a desired position, and securing the lever 38 in anappropriate stop 50 to maintain the desired axial position. This fineaxial adjustment of the axial movement of the shaft 18 is performedusing appropriate imaging equipment. The objective of this process stepis to ensure that the distal end of the cutting wire 20 is disposeddistally of the distal peripheral edge of the lesion 54, while at thesame time the proximal end of the cutting wire 20 is disposed proximallyof the proximal peripheral edge of the lesion 54. This will ensure theability to isolate the entire lesion 54 during the cutting procedure,with sufficient margins to minimize the chance that any portion of thelesion inadvertently remains behind in the patient's body followingremoval thereof.

When the distal tip 14 is in the precise position desired by thepractitioner, first lever 36, which is normally disposed in a firstdetent 58 (FIGS. 5 and 6) in the first slot 42, is actuated proximallyuntil it rests in a second detent 60 (FIG. 5) in the first slot 42. Thisaction retracts the sheath 30 proximally a sufficient distance topartially uncover the cutting element 20. It should be noted, however,that in some circumstances it may be desirable to fully retract thesheath, so that the entire cutting element 20 is released, in order tocreate a different cutting geometry. In such an instance, a detent 61(FIG. 7) is provided within the slot 42 to accommodate the lever 36 inthe fully proximal position necessary to achieve full axial retractionof the sheath. Additional intermediate detents 60 (not shown) may beprovided to retract the sheath to intermediate positions correspondingto various partial radial extension positions of the cutting element.

After the sheath 30 is retracted as desired, the third lever 40 may thenbe actuated distally along the third slot 46 to an intermediate stop 52,thereby causing the rod 32, and therefore the proximal end of thecutting element 20, to move axially a distance equivalent to thattraversed by the lever 40. This, of course, results in the partialradial expansion of the cutting element 20 to an arched or bowedconfiguration as shown in FIG. 8. The extended configuration of thecutting element 20 may define, when rotated about the instrument axis, aspherical cutting volume, as shown, or it may be configured to define anelliptical or toroidal cutting volume when the cutting element isrotated about the instrument axis 19, rather than a spherical volume.

Of course many other mechanisms for radially expanding the cuttingelement 20 may be utilized as well, within the scope of the invention.For example, since the wire 20 is preferably fabricated of a shapedmemory or superelastic material, the proximal retraction of the sheath30, and resultant release of the wire 20, may be sufficient to cause thecutting wire 20 to radially expand to its desired position.

Once the cutting element 20 is partially radially expanded as describedsupra, an inner portion of the target lesion 54 is isolated fromsurrounding tissue. To complete this step, the cutting element 20 isenergized by the electrosurgical generator (not shown), after which theknob 34 is rotated, either manually or via a motorized drive mechanism,to rotate the cutting element 20 through a 360 degree arc. Thisrotational cutting action functions to completely sever the innerportion of the tissue sample from the surrounding tissue, therebycutting off all blood supply to the inner tissue sample. Alternatively,if desired, the cutting element 20 may be simultaneously rotated andmoved axially, by moving the shaft 18 axially, in order to create a“corkscrew”-shaped tissue segment.

Once this initial isolation step is completed, the cutting element orwire 20 is preferably further radially extended to the position shown inFIG. 9. This is accomplished by sliding the lever 36 proximally toanother detent 60 to further proximally retract the sheath 30. Then, thethird lever 40 may be axially slid distally to another stop or detent 52to further radially extend the cutting wire 20. Once radiallypositioned, the cutting element 20 is energized by the electrosurgicalgenerator, after which the knob 34 is rotated to rotate the cuttingelement 20 through a 360 degree arc. This rotational cutting actionfunctions to completely sever a second segment of the tissue sample fromthe surrounding tissue, thereby cutting off all blood supply to thissegment as well.

These steps may be repeated as many times as desired, in order to ensurethat the tissue sample is segmented for efficient removal from thepatient's body. Ultimately, however, a final cut is preferably made, byfully retracting the outer sheath 30, using the slide lever 36, andfully extending the cutting wire 20, using the slide lever 40, so thatthe cutting element 20 extends radially beyond the periphery of thetarget lesion 54, as illustrated in FIG. 10. The cutting element is thenenergized with RF energy, in the same manner as previously, after whichthe knob 34 is rotated to rotate the cutting wire 20 through a completearc about the axis 19. At this point, the entire lesion 54 should becompletely isolated from surrounding tissue, with a sufficient marginabout the outer periphery thereof to ensure successful removal of theentire lesion.

During the foregoing segmentation process, if the cutting element 20remains charged by RF energy during the stepwise radial extensionprocess, the outer tissue rings will be further segmented radially.

Other segmentation approaches may be advantageously utilized as well, ifdesired. For example, rather than segmenting the tissue samplecircumferentially, from the inside out, the tissue sample may besegmented circumferentially from the outside in, i.e. by making an outercircumferential cut (FIG. 10), then partially retracting the cuttingelement 20 and cutting additional layers, as shown in FIGS. 8 and 9.Alternatively, the tissue may be sectioned by extending and retractingthe cutting element 20 radially, akin to “sectioning an orange”.Additional radially oriented cutting elements could be employed as wellto further segment the tissue.

An alternative approach to segmenting the tissue specimen to beretrieved is illustrated in the embodiment shown in FIGS. 17-19. In thisembodiment, wherein like elements to those in the embodiment of FIG. 1are designated by like reference numerals, succeeded by the letter a,there is shown a tissue retrieval or biopsy instrument 10 a, having adistal tip 14 a with an electrosurgical element or wire 16 a for cuttingtissue and thereby permitting advancement of the instrument into apatient's body. A shaft or cannula 18 a is disposed along an axis 19 aof the instrument. A longitudinal slot 66 is disposed axially along aportion of the length of the cannula 18 a. A cutting element or wire 20a, which is preferably an electrosurgical cutting element, is disposedso as to be extendable from and retractable into the slot. The cuttingelement is shown in a retracted position in FIG. 17, and in an extendedposition in FIGS. 18 and 19.

In operation, once the instrument 10 a has been positioned so that thedistal tip is adjacent to a lesion to be removed, in the mannerdescribed supra with respect to the embodiment of FIG. 1, the cuttingelement 20 a is charged with RF energy from a proximally disposedelectrosurgical generator (not shown). Then, the cutting element 20 a isradially extended by the practitioner, using a proximal controlmechanism (not shown), to a position as shown, for example, in FIG. 18.Once extended, the cutting element is moved axially in a proximaldirection along the slot 66, as illustrated by the arrow 68 and thephantom images of the cutting element 20 a, in order to isolate agenerally cylindrical tissue segment, as the cannula 18 a is rotatedabout its axis 19 a simultaneously.

FIG. 19 illustrates a procedure similar to that illustrated in FIG. 18,except that while the cutting element 20 a is being axially moved in aproximal direction as shown by arrows 70, it is also deployed to variousradial heights, in order to create a variable height cut.

Once segmentation of the tissue sample has been completed, whicheverembodiment has been employed, each tissue segment can be withdrawn usinga suitable retrieval apparatus. Preferably, the tissue segments arewithdrawn through a cannula, such as the sheath 30, using such means asa suction grasper, flexible mechanical grassers, an auger conveyor, aprickly bristle or brush grasper, a wire retrieval basket, or the like.

The foregoing procedure and apparatus may be used for either adiagnostic or a therapeutic purpose. It is particularly advantageous fora diagnostic procedure because the resultant incision from the procedurewill not substantially exceed in length the diameter of the cannula. Onthe other hand, a second preferred embodiment, illustrated in FIGS.11-16, is particularly suited to a therapeutic procedure, wherein it ishighly desired to ensure that the entire lesion of interest is removedin one step, without segmenting that lesion within the body. Thisapproach emphasizes maximum safety, in that only a single procedure isnecessary, assuming the tissue sample margins are clean, and theincision necessary to remove the intact tissue sample is of the minimumsize necessary to remove the sample. With this procedure, there is alsoa somewhat reduced risk of cell migration from the specimen to thesurrounding tissue, since as described below, the specimen isencapsulated as soon as it is isolated and then promptly removed. Nosegmentation of the specimen occurs within the patient's body.

Referring now to FIGS. 11-14, wherein like elements to those in thefirst embodiment are identified by like reference numerals, followed bythe letter “b”, there is shown the distal end or disposable wand portion12 b of an instrument 10 b. The portion 12 b includes a distal tip 14 b,which may be constructed in a manner similar to that of tip 14 in FIG.1, a shaft 18 b, and a sleeve 30 b. Disposed in a radially retractedorientation in a recess 48 b of the shaft 18 b are a plurality ofencapsulation elements or bands 72, one of which also comprises a singleelectrosurgical cutting element 20 b. For the purposes of the inventionit is unimportant which of the encapsulation elements 72 may be chargedby means of RF energy to form an electrosurgical cutter, and in certaininstances it may be advantageous to employ a plurality of cuttingelements. Each of the encapsulation elements 72 and the cutting element20 b are attached at their distal ends to the distal end of the shaft 18b, at its connection with the distal tip 14 b of the instrument 10 b,which connection is preferably accomplished by means of a keyway 74.

The proximal end of the instrument 10 b may be substantially the same asthat for the instrument 10, illustrated in FIGS. 4-7, comprising areusable driver portion having an actuator for axially moving the sheath30 b between proximal and distal positions, a linear actuator foraxially moving the shaft 18 b, an actuator for rotationally moving theshaft 18 b, and an actuator for axially moving the proximal ends of theencapsulation elements 72 and cutting element 20 b, in order to radiallyextend and retract each of the elements 72 and 20 b, as illustrated inFIGS. 14-16.

In operation, as with the first embodiment of FIG. 1, when it isdetermined that either a diagnostic or therapeutic biopsy procedure isindicated, the distal disposable wand portion 12 b of the instrument 10b will be moved axially to a position wherein the distal tip is adjacentto and distally of a target lesion, using the stereotactic rail 26 andassociated imaging system. During this process step, wherein grosslinear movement of the wand 12 b is controlled by the rail system 26,the electrosurgical cutting element (not shown) on the distal tip 14 bis energized to pierce and cut through the patient's body tissue topermit distal advancement of the wand 12 b to the region surrounding thelesion.

Once the distal tip 14 b is generally in the desired position adjacentto the target lesion, using the stereotactic rail 26, the second lever38 is actuated to provide fine tuning of the axial position of thedistal tip 14 b relative to the lesion, by moving the shaft 18 b axiallyto a desired position, and securing the lever 38 in an appropriate stop50 to maintain the desired axial position. This fine axial adjustment ofthe axial movement of the shaft 18 b is performed using appropriateimaging equipment. The objective of this process step is to ensure thatthe distal end of the cutting wire 20 b is disposed distally of thedistal peripheral edge of the lesion, while at the same time theproximal end of the cutting wire 20 b is disposed proximally of theproximal peripheral edge of the lesion. This will ensure the ability toisolate the entire lesion during the cutting procedure, with sufficientmargins to minimize the chance that any portion of the lesioninadvertently remains behind in the patient's body following removalthereof.

When the distal tip 14 b is in the precise position desired by thepractitioner, first lever 36, which is normally disposed in a firstdetent 58 (FIGS. 5 and 6) in the first slot 42, is actuated proximallyuntil it rests in a second detent 60 (FIG. 7) in the first slot 42. Thisaction retracts the sheath 30 b proximally a sufficient distance tocompletely uncover the cutting element 20 b and associated encapsulationelements 72. The third lever 40 may then be actuated distally along thethird slot 46 to the distal-most stop 52, thereby causing the rod 32,and therefore the proximal ends of the cutting element 20 a andencapsulation elements 72, to move axially a distance equivalent to thattraversed by the lever 40. This, of course, results in the radialexpansion of the cutting element 20 b and encapsulation elements 72 toan arched or bowed configuration as shown in FIG. 14, wherein thecutting element 20 b defines a peripheral boundary which lies radiallybeyond the peripheral boundary of the lesion, as in the case of thefirst embodiment shown in FIG. 8. Again, it should be noted that thecutting element and encapsulation elements need not be fully extended,especially if an ellipsoidal or toroidal cutting geometry is desired, inwhich case intermediate stop 61 is utilized.

Once the cutting element 20 b and associated encapsulation elements 72are radially expanded as described supra, it is time to isolate thetarget lesion from surrounding tissue. Advantageously, a spherical ortoroidal tissue sample having a radius of at least 15 mm may be definedand isolated by rotating the cutting element 20 b about the axis of theshaft 18 b. The encapsulation elements 72 will also be rotated duringthis process, but their function is not yet important. To complete theisolation step, the cutting element 20 b is energized by theelectrosurgical generator (not shown), after which the knob 34 isrotated, either manually or via a motorized drive mechanism, to rotatethe shaft 18 b, and thus the cutting element 20 b through a 360 degreearc. This rotational cutting action functions to completely sever thetissue sample from the surrounding tissue, thereby cutting off all bloodsupply to the tissue sample (and thus from the lesion, which should becompletely contained within the tissue sample).

After the isolation step is completed, the isolated tissue sample may beretrieved from the patient's body 56. This retrieval step may beaccomplished in a number of ways, but it is the objective in connectionwith the illustrated embodiment to encapsulate and remove the isolatedtissue sample in one piece. Accordingly, as is illustrated in FIGS. 15and 16, continued rotation of the shaft 18 b, once the isolation stephas been completed, preferably with the cutting element 20 bde-energized, will twist and tighten the encapsulating elements 72 andthe cutting element 20 b about the tissue sample (not shown). As theshaft 18 b is rotated, and the encapsulating elements 72 radiallyretracted and twisted, they will function to deform the tissue sampleradially so that it is more compact and more securely retained withinthe spaced defined by the encapsulating elements 72.

Once the tissue sample has been fully encapsulated, the tissue samplemay be removed from the patient's body. Advantageously, since the tissuesample is larger in cross-section than the cross-section of the sheath30 b, the inventors have developed an inventive approach for removalthereof which results in minimum trauma and incision size for thepatient while still permitting the removal of an intact specimen. Toremove the specimen, the sheath 30 b is retracted proximally, followingwhich the cutting element 20 b is again energized by the electrosurgicalgenerator. The shaft 18 b, with the tissue specimen encapsulatedthereabout, is then proximally withdrawn by the practitioner, with thecutting element 20 b functioning to cut through the tissue necessary tocreate a passage for exit of the sample. Once the unit, including theshaft and encapsulated tissue mass, is completely withdrawn from thebody, the incision created by the cutting element 20 b upon withdrawalfrom the body may be adhesively closed, with minimal required follow-upcare and scarring.

Many alternative embodiments may be used to accomplish the methodoutlined supra, which essentially involves isolating the tissue massfrom surrounding tissue, encapsulating the tissue mass in place about ashaft, then removing the encapsulated tissue mass and shaft from thebody by energizing an RF electrosurgical cutter to cut its way out,without the need for a cannula or pre-existing incision. For example, aplurality of cutting elements could be employed, or a separate cuttingelement could be disposed on the shaft. An important aspect of theinvention, of course, is a relatively high likelihood of acquiring theentire lesion of interest in a single therapeutic procedure, without theneed for follow-up surgery.

While this invention has been described with respect to various specificexamples and embodiments, it is to be understood that the invention isnot limited thereto and that it can be variously practiced within thescope of the following claims.

1. A biopsy instrument comprising an elongated shaft, a longitudinalaxis, a distal end on the shaft, a tissue cutting surface on the distalend of the shaft to facilitate advancement of the instrument throughtissue to a target biopsy site, a radially expandable elongatedelectrosurgical cutting element which is longitudinally disposed on andhas proximal and distal ends secured to and supported by a distalportion of the shaft proximal to the distal end of the shaft and whichis configured to receive RF energy from a source thereof for severing atissue specimen from the target site within a patient's body by rotatingthe electrosurgical cutting element in a radially expanded conditionabout the longitudinal axis to create a peripheral boundary about thetissue specimen and at least one encapsulating element which is securedto the distal portion of the shaft and which is configured toencapsulate the severed tissue specimen, so that the entire severedtissue specimen may be withdrawn from the patient's body.
 2. The biopsyinstrument as recited in claim 1, wherein the encapsulating elementcomprises a band which is disposed along the shaft and which isactuatable between a radially retracted position and a radially extendedposition.
 3. The biopsy instrument as recited in claim 1, wherein saidencapsulating element comprises a plurality of bands disposed along saidshaft, each of said bands being actuatable between a radially retractedposition and a radially extended position.
 4. The biopsy instrument asrecited in claim 3, wherein said electrosurgical cutting elementcomprises one of said encapsulating elements.
 5. The biopsy instrumentof claim 1 wherein the at least one element for encapsulating the tissuespecimen has a leading edge which advances over the cut tissue specimen.6. The biopsy instrument of claim 1 wherein the at least oneencapsulating element is configured to encapsulate the tissue specimenas the elongated shaft is rotated about the longitudinal axis.
 7. Aninstrument for retrieving a tissue specimen from a target site in apatient's body, comprising: an elongated shaft having a longitudinalaxis, a distal end and a first tissue cutting member on the distal endconfigured to penetrate through tissue to facilitate entry of theinstrument into the patient's body and advancement therein to the targetsite and a distal shaft portion proximal to the distal end; anelectrosurgical tissue culling element longitudinally disposed on thedistal shaft portion of the elongated shaft proximal to a distal end andhaving proximal and distal ends secured to and supported by the distalshaft portion and configured to receive RF energy from a source thereofin order to sever a tissue specimen from the target site by rotatingabout the longitudinal axis and create a peripheral boundary about thetissue specimen; and at least one encapsulating element which is securedon the distal portion of the elongated shaft and which is configured toencapsulate the severed tissue specimen so that the entire tissuespecimen may be withdrawn from the patient's body.
 8. The instrument asrecited in claim 7, wherein said encapsulating element comprises anaxially disposed band, said band being actuatable between a radiallyretracted position and a radially extended position.
 9. The instrumentas recited in claim 7, wherein said encapsulating element comprises aplurality of bands disposed along the longitudinal axis, each of thebands being actuatable between a radially retracted position and aradially extended position.
 10. The instrument as recited in claim 9,wherein said instrument is rotatable about the longitudinal axis inorder that said bands may be twisted for encapsulating said tissuespecimen.
 11. The instrument as recited in claim 7, wherein theelectrosurgical cutting element is axially aligned, is actuatablebetween a radially retracted position and a radially extended position,and is rotatable about the axis in said radially extended position toisolate the desired tissue specimen from surrounding tissue at thetarget site by defining a peripheral margin about the tissue specimen.12. The instrument as recited in claim 7, and further comprising asheath which is axially movable between distal and proximal positionsfor selectively covering and uncovering the encapsulating element. 13.The Instrument as recited in claim 7, wherein the electrosurgical tissuecutting element is actuatable to cut tissue as said instrument isproximally withdrawn from said patient's body with said encapsulatedintact tissue specimen.
 14. The instrument of claim 7 wherein the atleast one encapsulating element is configured to encapsulate the tissuespecimen as the elongated shaft is rotated about the longitudinal axis.15. A method for obtaining a tissue specimen from a target site within apatient's body, comprising: providing an instrument having an elongatedshaft, a distal end, a distal shaft portion proximal to the distal end,a longitudinal axis, at least one encapsulating element disposed on thedistal shaft portion and an axially disposed electrosurgical cuttingelement on the distal shaft portion thereof, inserting the instrumentinto the patient's body and advancing the instrument therein until thedistal shaft portion is disposed in the target site from which thetissue specimen is to be taken; radially extending the electrosurgicalcutting element on the distal shaft portion; rotating the radiallyextended electrosurgical cutting element about the longitudinal axiswhile the electrosurgical cutting element is energized with RF energy tocut tissue to create a peripheral boundary about the tissue specimen, toisolate the tissue specimen from surrounding tissue in the target site;radially extending at least one encapsulating element and rotating theat least one encapsulating element about the isolated tissue specimen toencapsulate the entire isolated tissue specimen; and withdrawing theentire encapsulated tissue specimen from the patient's body.
 16. Themethod as recited in 15, wherein said at least one encapsulating elementcomprises a plurality of bands which are disposed axially along saidinstrument.
 17. The method as recited in claim 15, and furthercomprising proximally withdrawing said instrument, with the encapsulatedtissue specimen, from the patient's body, and including cutting tissueas the instrument is withdrawn.
 18. The method of claim 15 wherein theisolated tissue specimen is encapsulated as the electrosurgical cuttingelement is rotated about the axis.
 19. An elongated device forretrieving a tissue specimen separated from a target site, comprising:a. an elongated shaft having a longitudinal axis, proximal and distalends and a distal portion proximal to the distal end; b. a thinelectrosurgical tissue cutting electrode secured to the distal end ofthe elongated shaft having a blunt arcuate activatable tissue cuttingportion spaced distally from the distal end of the shaft and configuredto be electrically connected to a high frequency electrical powersource; and c. at least one encapsulating element which is secured on adistal portion of the elongated shaft and which is configured toencapsulate a separated tissue specimen so that the entire tissuespecimen may be withdrawn from the patient's body.
 20. The elongatedaccessing device of claim 19 wherein the thin electrode secured to thedistal end of the elongated shaft is formed of conductive metallicmaterial.
 21. The elongated accessing device of claim 19 wherein thedistal shaft portion of the elongated shaft is provided with a secondtissue cutting member spaced proximally from the distal end of theelongated shaft.
 22. The elongated accessing device of claim 21 whereinthe second tissue cutting member spaced proximally from the distal endof the elongated shaft has a radially unexpanded configuration and aradially expanded configuration.
 23. The elongated accessing device ofclaim 22 wherein the second tissue cutting member is at least in partarcuate in shape when in a radially expanded configuration.
 24. Theelongated accessing device of claim 23 wherein the second tissue cuttingmember on the distal shaft portion is rotatable about the longitudinalaxis of the elongated shaft.
 25. The elongated device of claim 19wherein the at least one element is configured to encapsulate the tissuespecimen by rotation about the longitudinal axis.
 26. A biopsy device,comprising: a tubular member having a distal end, a tissue penetratingdistal tip on the distal end and a distal portion proximal to the distalend; an electrosurgical cutting tool which has a distal end and aproximal end and both ends are attached to the distal portion of thetubular member proximal to the distal end of the tubular member, whichis configured to selectively bow out of and retract into an opening inthe distal portion of the tubular member and which is configured tosever a tissue specimen from a biopsy; and a tissue encapsulation deviceattached at least to the distal portion of the tubular member forencapsulating the entire severed tissue specimen.
 27. A biopsy device,comprising: a single use disposable tubular member formed of polymericmaterial having an elongated electrosurgical tissue cutting tool with aproximal end and a distal end attached to a distal portion of thetubular member proximal to a distal tip and at least a distal portion ofthe electrosurgical cutting tool which is configured to selectively bowaway from an exterior portion of the tubular member and which isconfigured to receive RF energy from a source thereof so as to create aperipheral boundary about a tissue specimen so as to sever the tissuespecimen from surrounding tissue; and a single use disposable tissueencapsulation device externally attached at least to the distal portionof the tubular member for encapsulating the severed tissue specimen. 28.A method for obtaining a tissue specimen from a target site within apatient's body, comprising: a. providing a tissue obtaining instrumenthaving an elongated shaft, a distal end, a longitudinal axis, a distalshaft portion proximal to the distal end and a radially expandableelectrosurgical cutting element end on the distal shaft portion; b.advancing the tissue obtaining instrument into the patient's body untilthe distal shaft portion of the instrument is disposed in the targetsite from which the tissue specimen is to be taken; c. radiallyextending the electrosurgical cutting element away from the elongatedshaft so that at least a portion thereof has an arcuate; d. rotating theradially extended arcuate shaped electrosurgical cutting element aboutthe longitudinal axis of the instrument while energizing the cuttingelement with RF energy to cut a tissue specimen from surrounding tissueat the target site by creating a peripheral boundary about the tissuespecimen; e. encapsulating the entire cut tissue specimen; and f.removing the entire encapsulated tissue specimen and the tissueobtaining instrument from the patient.
 29. The method of claim 28wherein the cut tissue specimen is encapsulated as the radiallyextended, arcuate shaped electrosurgical element is rotated about thelongitudinal axis.
 30. A biopsy instrument comprising an elongated shafthaving a distal end and a distal shaft portion proximal to the distalend, an electrosurgical cutting element on the distal shaft portionconfigured to receive RF energy from a source thereof for severing atissue specimen from a target site within a patient's body by creating aperipheral boundary about the tissue specimen and at least one means forencapsulating the entire severed tissue specimen, so that the entirespecimen may be withdrawn from the patient's body.
 31. The biopsyInstrument of claim 30 wherein the at least one means for encapsulatingthe severed tissue specimen is configured to encapsulate the severedtissue specimen as the cutting element is rotated about the longitudinalaxis of the shaft.
 32. An instrument for retrieving a tissue specimenfrom a target site in a patient's body, comprising: an elongated shafthaving a distal end configured for entry into a patient's body and adistal shaft portion proximal to the distal end; and a electrosurgicaltissue cutting means on the distal shaft portion of the elongated shaftconfigured to receive RF energy from a source thereof to sever a tissuespecimen from the target site by creating a peripheral boundary aboutthe tissue specimen; and at least one means on the distal shaft portionof the elongated shaft for encapsulating a tissue specimen, so that theentire specimen may be withdrawn as a single unit from the patient'sbody.
 33. The instrument of claim 32 wherein the at least one means forencapsulating a tissue specimen is configured to encapsulate the tissuespecimen as the cutting element is rotating about the longitudinal axisof the elongated shaft.
 34. A biopsy device, comprising: an elongatedshaft having a tissue penetrating distal tip and a distal shaft portionproximal to the distal tip; an electrosurgical cutting means having adistal end attached to the distal shaft portion which is configured toselectively bow out of a recess in the distal shaft portion and toretract into the opening recess and which is configured to receive RFenergy from a source thereof to sever a tissue specimen from the targetsite by creating a peripheral boundary about the tissue specimen; and atissue encapsulating means attached at least to the distal shaft portionof the elongated shaft for encapsulating the entire severed tissuespecimen.
 35. The biopsy device of claim 34 wherein the tissueencapsulating means is configured to encapsulate the entire tissuespecimen as the biopsy device or a portion thereof is rotated.
 36. Abiopsy device, comprising: a single use disposable elongated shafthaving a distal tip, a distal shaft portion proximal to the distal tip,an electrosurgical cutting tool attached to and supported on the shaftportion and at least a part of the cutting tool being configured toselectively bow away from the distal shaft portion and to receive RFenergy from a source thereof to sever a tissue specimen from a targetsite by creating a peripheral boundary about the tissue specimen; and asingle use disposable tissue encapsulating means externally attached atleast to the distal shaft portion for encapsulating an entire severedtissue specimen.
 37. The biopsy device of claim 36 wherein theencapsulating means is configured to encapsulate the tissue specimen asthe biopsy device is rotated.
 38. A method for obtaining a tissuespecimen from a target site within a patient's body, comprising: a.providing a tissue obtaining instrument having an elongated shaft, adistal end, a distal shaft portion proximal to the distal end, alongitudinal axis, and an axially disposed radially expandableelectrosurgical cutting element secured to the distal shaft portion; b.advancing the tissue obtaining instrument into the patient's body untilthe distal portion of the instrument is disposed in the target site fromwhich the tissue specimen is to be taken; c. radially extending theelectrosurgical cutting element away from the distal shaft portion in anarcuate shape; d. rotating the radially extended arcuate shapedelectrosurgical cutting element about the longitudinal axis of theinstrument while energized with RF energy to sever a tissue specimenfrom surrounding tissue at the target site by creating a peripheralboundary about the tissue specimen; e. encapsulating the entire severedtissue specimen; and f. removing the encapsulated entire severed tissuespecimen and the tissue obtaining instrument from the patient.
 39. Themethod of claim 38 wherein cut tissue specimen is encapsulated as theelectrosurgical cutting element is rotated in the arcuate shape.
 40. Aninstrument for separating a tissue specimen from a target site in apatient's body, comprising: an elongated shaft having a longitudinalaxis, a distal end configured for entry into a patient's body and adistal shaft portion proximal to the distal end; and a single RF poweredelectrosurgical tissue cutting element on the distal shaft portionconfigured to bow radially outwardly away from the distal shaft portionand to sever a tissue specimen from the target site by rotating aboutthe longitudinal axis of the shaft in the bowed configuration to createa peripheral boundary about the tissue specimen; and an encapsulatingassembly on the distal shaft portion which is configured to encapsulatethe entire tissue specimen severed from the tissue site by the bowedelectrode so that the entire severed tissue specimen may be withdrawnfrom the patient's body.
 41. The instrument as recited in claim 40,wherein said encapsulating element comprises at least one axiallydisposed band which is actuatable between a radially retracted positionand a radially extended position.
 42. The instrument as recited in claim40, wherein the elongated shaft is rotatable about the longitudinal axisin order to twist the bands of the encapsulating assembly to encapsulatethe tissue specimen.